Paypal Express Checkout - 500 Server Error

Hi everyone,
I need help on Paypal Express Checkout. I've installed and added the button on checkout. It's in sandbox mode. When you hit the paypal express button without logging in as customer, it goes to the paypal, sign in, and finishing the transaction works fine but after that it redirect to my site: index.php?route=payment/pp_express/expressConfirm > I get an Server Error 500.
I've contact Paypal and send in the debug code. They said it's working fine on their end. Here's their message:
"I tried to do a few checkout in your website and I could see the 500 error page when I click the “Check out with PayPal” button.

But this time the error occurred athttp://52.193.67.110/index.php?route=payment/pp_express/expressConfirm but not PayPal page.

Also I cannot reproduce the PayPal 500 error page in your error log during my testing (2016-01-12 0:29:01 - 2016-01-12 0:45:22)

Since the error is only happened with I use the “Check out with PayPal” button (we call the shortcut flow), if I fill in the form and then select PayPal Express Checkout to checkout, it will be fine. According to my experience, some shopping cart will crash when you try to complete an order that is not exist in the shopping cart system. With using the shortcut flow, it will first go to PayPal and back to your system to generate the order. I will suggest you check the expressConfirm function which should be located at pp_express.php see whether part of the code rejected shortcut flow."

So I send in a ticket to Opencart about this and they can't figure it out either so they redirected me here. I also contact MultiMerch and Dreamvention if they get any inference with the module and they said it works fine with theirs. I have a Journal 2 theme and I've change it back to default but I got the same results of 500 server error.

My opencart version is 2.1.0.2.

Any help will be appreciated. Thanks

Michael

Also I found the error: Fatal error: Class 'Controllermodule' not found in /opt/bitnami/apps/opencart/htdocs/vqmod/vqcache/vq2-system_storage_modification_system_engine_loader.php on line 52

First fix your ISE 500 error:
http://forum.opencart.com/viewtopic.php?f=170&t=50555


The ControllerModule error I've found related to theme modules (like pav) when they are loaded from a custom location. If you are using a custom theme that has their own modules that aren't in the normal module area that might be the cause.

Hi Qphoria,
I've been contacting the theme developer about this issue and they said since it doesn't work with the default theme either then it isn't their issue. Do see any case similar to this using a Journal 2 theme and a MultiMerch plugin? I'll try to troubleshoot it more.

mnyght wrote:Hi Qphoria,
I've been contacting the theme developer about this issue and they said since it doesn't work with the default theme either then it isn't their issue. Do see any case similar to this using a Journal 2 theme and a MultiMerch plugin? I'll try to troubleshoot it more.

It is not a theme issue.
Quick Tip...
There are 4 types of extension: Payment, Shipping, Total, and Module.
Shipping and Order Total issues are NEVER theme related
Payment issues SHOULD NEVER be theme related, UNLESS the theme developer included a payment folder which he should never do
Modules CAN be theme related because they are not done correctly in OpenCart IMO. Modules should only have the code that pertains to the module and NOT the module wrapper code. That should be moved to the column, top, and bottom tpl files.

Your issue is a server setting that hides the real error. Follow that guide I sent to see the real error so you can see what the problem really is.

Yes, I have enabled the error handling in the index.php so I get the same error message on log too: It only works when I logged in. It's in sandbox mode and debugger is on.

Also I installed a fresh and latest opencart on a different server with only the paypal express checkout and paypal button modules. I got a similar error without logging in: What exactly you meant by:

"Modules should only have the code that pertains to the module and NOT the module wrapper code. That should be moved to the column, top, and bottom tpl files."

Do I move the module in the layout?

I have found the fix here: https://github.com/opencart/opencart/issues/3626
The module needs to be updated for other users. Thanks for your time